Using 4chord MIDI

First off, all I can tell about here refers to Linux. But since 4chord MIDI implements standard USB and MIDI specifications, other operating systems should treat it also as a normal MIDI device, so any general MIDI setup
instructions should work just fine.

I usually use JACK for audio routing and Ardour for recording in general, and a2jmidid,
Calf plugins and Fluidsynth sound fonts for MIDI in particular. I never used Rosegarden, MusE
or anything alike, but then again, 4chord MIDI is a regular USB MIDI device, so it should work as any other MIDI controller.

Plug it in

Connect 4chord MIDI to your computer and check if it got recognized. Since it uses the V-USB library for USB handling, dmesg should show something like this:

The VID/PID pair (16c0:05e4) should be the same, the Device number is most likely different.

Simple playback

Before going too deep into home recording under Linux etc, simple playback can be achieved with ALSA as well.
For Ubuntu, the required packages are alsa-tools fluidsynth fluidsynth-soundfont-gm, for any other distribution ..well, I guess they should have similar names?